During both washing and drying of clothes it is common to treat various types of fabrics such as wool, cotton, silk, nylon, polyester, permanent-press, and the like with treating agents such as anti-static, anti-bacterial or deodorant agents which condition fabric, soften fabric, and reduce fabric tangling, knotting or wrinkling.
The fabric treating agents have been added to wash or rinse cycles of clothes washers and have successfully treated fabrics. However, adding the fabric treating agents to rinse water can result in the release of substantial amounts of polluting agents. Further, the addition of a fabric treating agent to a wash cycle or to a rinse cycle can be easily forgotten and the fabric treating agent can be easily mismeasured.
In recent years increasing attention to the addition of fabric treating compositions to machine dryers has occurred. Fabric treating compositions have been sprayed or coated onto the machine drum as is shown in U.S. Pat. Nos. 2,812,593; 2,846,276; 3,002,288; and 3,650,816. Fabric treating compositions have been coated on flexible substrates that can act as a single use fabric treating releasing means acting by mechanical contact and are shown in U.S. Pat. Nos. 3,442,692; 3,686,025; and 4,149,977. These methods of adding fabric treating agents suffer from the drawback that they commonly must be added to the dryer with each load of damp clothes.
In response to a need for providing fabric treating compositions to dryer loads using means that can be placed in the drum to provide a controlled release of fabric treating material for a number of drying cycles (10 or more), a flexible fabric pouch or envelope having a fabric treating composition which is slowly released during each drying cycle was proposed, see for example U.S. Pat. Nos. 3,870,145; 3,967,008; 4,004,685; and 4,098,937. The compositions in these fabric treating means commonly include two fabric treating agents having a high temperature and a low temperature softening point which can provide a somewhat controlled release of fabric treating agent over a spectrum of temperatures in the drying cycle. These systems can suffer from the drawback that the treating compositions can be released at differing rates at differing temperatures through the drying cycle, and at high temperature the treating means can release sufficient treating agent that clothes can become marked, spotted or soiled by the fabric treating agent.
The control over release of treating agent over a range of temperatures was obtained to a certain extent by including in the softening compositions disclosed in U.S. Pat. No. 4,149,977 a softening or anti-static amount of a quaternary tetrahydrocarbyl-ammonium compound, a softening point depressant for the quaternary ammonium compound comprising an alkanol amide, and a viscosity modifier comprising silica. The quaternary ammonium compound and the alkanolamide compositions interact and reduce the softening point of the fabric treating composition, and the silica controls viscosity. However, the release rates can vary substantially at dryer operating temperatures between about 40.degree. C. and 90.degree. C. However, even in this controlled system substantial amounts of treating agent can be released at high temperature, staining, marking or spotting clothes in the dryer load.
Clearly a substantial need exists to provide a composition that changes little in viscosity and release rate in response to change in temperature and at a rate substantially less than prior fabric treating agents.